Propenyl derivatives of 2, 2-dimethyl-5-hydroxycoumaran as antioxidants



PROPENYL DERIVATIVES OF 2,2-DIMETHYL-5- HYDROXYCOUMARAN AS ANTIOXIDANTSAlan Bell, M. B. Knowles, and Clarence E. Tholstrup,

Kingsport, Tenn., assignors to Eastman Kodak Company, Rochester, N. Y.,a corporation of New Jersey No Drawing. Application April 7, 1954,Serial No. 421,674

Claims. (Cl. 260-3985) This invention relates to the stabilization offats, oils, or other organic materials subject to deteriorationemploying one or more related compounds as an antioxidant, namely2,2-dimethyl 5 hydroxy-x-(l-propenyl)- coumaran.

This application is a continuation in part of our copending applicationfiled May 31, 1951, Serial No. 229,282, now United States Patent No.2,682,474 dated June 29, 1954.

Various derivatives of 2,2 dimethyl 5 hydroxycoumaran are known whereinalkyl, aryl and cycloaliphatic radicals aresubstitutedin the 6-position.Such compounds are said to be suitable for the stabilization of crackedgasoline and otherrelated organic compounds although it appears thatthey can also be used for the stabilization of fats, oils or the like.

We have now found that a l-propenyl substituent in what is probably the6-position produces an unexpectedly superior and quite valuableantioxidant for organic materials, especially fats andoils. Thiscompound probably has the following structural formula:

It is believed significant to note that the l propenyl radical in the6-position contains a double bond in conjugated relationship to thedouble bond in the benzene ring. This is one of the distinguishingcharacteristics of thepropenyl derivatives covered by this application,the

parent application and our application Serial No. 229,281 filed on May31, 1951, now United States Patent No. 2,682,563 dated June 29, 1954. Itis believed that this conjugated relationship of the double bonds is ina large measure responsible for the unusual antioxidant properties of2,2 dimethyl 5 hydroxy x (l-propenyl) coumaran.

The discovery of the existence of improved antioxidant properties whichprobably results from the above-described conjugated double bondrelationship is unexpected inasmuch as the antioxidant propertiescreated by various nuclear substituents on compounds such as coumaran isbut little understood. It is believed advantageous that this antioxidantcompound be employed in monomeric form; however, the presence of acertain amount of low polymer is probably not especially objectionable.The propenylderivative with which this application is concerned is arelatively stable monomeric compound (or compoundmixture) which does notreadily polymerize. This compound is clearly distinct from thecorresponding allyl isomer. If the l-propenyl radical of thisantioxidant of this invention is replaced by an allyl or by a tertiarybutyl radical the protection factor in lard at a concentration of 0.02%is reduced to about one half or less as indicated by tests which havebeen tates Patent particularly useful in the stabilization of fats andoils.

Another object of our invention is to provide a process for thestabilization of such fats and oils employing2,Z-dimethyl-S-hydroxy-x-(1-propenyl)coumaran as the novel antioxidant.Other objects are apparent elsewhere in the specification.

Although the applicants believe that the structural formula of theantioxidant covered by this invention is that which has been describedabove, it is quite possible that the l-propenyl radical may be in the4-position instead of the 6-position, although this would not; appearmost probable. Nevertheless, the applicants do not wish to be limited tothe structural configuration depicted above. The antioxidant of thisinvention can be more generically depicted for the following structuralformula:

wherein R represents a substituent selected from the contain a1-propenyl radical in the 4-position as well as in the 6-position or itmay be so substituted in both positions. In order to insure that theterminology of this application covers the applicants contribution tothe art, the antioxidant product is designated as 2,2- dimethyl 5hydroxy-x-(l-propenyl)coumaran where x represents either or both of the4 or 6 positions (the l-propenyl radical obviously appearing twice inthe event that x represents both positions).

Example.2,Z-dimethyl-S-hydroxy-x-(1-pr0penyl)- coumaran It has also beenfound that cyclic ethers having the following formula are remarkablypotent antioxidants:

tests that have been conducted. Thus, these cyclic ethers show greatlyimproved antioxidant properties when the l-propenyl radical is presentas compared to those defined in U. S. Patent No. 2,535,058 wherein theposition occupied by the l-propenyl radical is occupied by a hydrocarbonradical such as a tertiary butyl radical. The cyclic ether in theformula set forth above can be prepared as set forth in the examplebelow; however, it has not yet been determined with certainty that thel-propenyl radical is in the 6-position. Some of the product may containthis radical in the 4-position as well as in the 6-position or may bedisubstituted in both positions. Thus the product prepared according tothe following procedure can be termed2,2-dimethyl-5-hydroxy-x-(1-propenyl)coumaran where x represents eitheror both of the 4 and 6 positions:

STEP 1.- PREPARATION F ALLYL ETHER 0}? 2,2-

DIMETHYL-t'J-HYDROXY COUMARAN To a solution of 117 grams (0.7 mole) of2,2-dimethyl- S-hydroxy coumaran and 36 grams (0.8 mole) of sodiumhydroxide in 250 cc. of methanol and 70 cc. of water, 84 grams (1.1moles) of allyl chloride was added. The mixture was stirred and refluxedfor four hours. At the end of this period, the reaction mixture wasadded to 2 volumes of ice water, and the organic layer extracted withether. The ether extract was washed twice with percent aqueous sodiumhydroxide solution and then four times with water. The ether solutionwas dried over calcium chloride, and the solvent then removed by heatingon a steam plate.

STEP 2.REARRANGEMENT OF ALLYL ETHER OF 2,2- DIMETHYL-5-HYDROXY COUMARANThe crude allyl ether prepared in Step 1 was mixed with 40 grams ofdimethylaniline and the solution heated at 230-235 .C. for 45 minutes.After cooling to room temperature, 150 cc. of ether was added and thedimethylaniline was removed by extracting with dilute hydrochloric acid.The ether solution was washed with water and then extracted with two300-cc. portions of percent aqueous sodium hydroxide solution. The ethersolution, after washing and then drying over calcium chloride, wasevaporated to yield 50 grams of 2,2-dimethyl-S-allyloxy coumaran whichhad not rearranged.

The aqueous extract was acidified. and extracted with ether. The etherextract was washed twice with water, dried over calcium chloride, andthe ether stripped ofi by heating on a steam plate. The crude productwas distilled to give '71 grams of an oil and 7 grams of residue. Thephysical constants determined for the 2,2-dimethyl- S-hydroxy-x-allylcoumaran were as follows: B. P.: 132135 C. at 2 mm.; n =1.5462.

STEP 3.P-REPARATION OF 2,2-DIMETHYL-5-HYDRO'XY- X-PROPENYL COUMARANSixty grams of potassium hydroxide pellets and 30 cc. of water werestirred and heated to 130 C. 'The reaction vessel was flushed out withnitrogen and then 30 grams of 2,2- dimethyl-S-hydroxy-x-allyl coumaranwas added. The mixture was stirred and heated at 160 C. for 30 minutes.The reaction product was immediately poured onto 150 cc. of ice waterand the mixture was acidified with dilute hydrochloric acid. The productwas extracted into a 1:1 ether-benzene mixture, the organic solutionwashed three times with aqueous sodium chloride solution, and then driedover calcium chloride. After removing the solvent, the propenylderivative was distilled at ll0-118 C. (0.1 mm.); n 1.5710.

It is believed quite clear that the process outlined in the precedingsteps described under the 'example'could be suitably modified by thoseskilled in the art to produce similarresults. Itis'believed-evident-that the 'l-propenyl derivatives of2,2-dimethyl-S-hydroxycoumarari can be prepared from the allyl analogsof these compounds by heating in the presence of 'any alkali metalhydroxide solution in water or other inert polar medium such as ethyleneglycol under an inert atmosphere at an elevated temperature followed bycooling, neutralization and separation of the product which can befurther purified by any other means such as by distillation at a greatlyreduced pressure or by recrystallization from an inert solvent such ashexane. Temperatures which can be advantageously employed during theheating step range from about C. to C.

The employment of 2,2-dimethyl-S-hydroxy-x-(l-properryl) coumaran as anantioxidant for fats and oils'has been indicated above. When soemployed, fractions of a percent of such compounds can be incorporatedinto such materials as cottonseed oil, peanut oil, etc. by mixing theantioxidant with the fats or oils whereby a solution or dispersion ofthe antioxidant in the substrate is obtained. Alternatively theantioxidant can be blended with suitable solvents to form an antioxidantsolution employing solvents well known in the art. Such antioxidantsolutions can be more readily dissolved in the fat or oil to bestabilized with less necessity for prolonged mixing of the fat or oilthan when the undissolved antioxidant is employed.

Synergists can be admixed with the fats or oils along with theundissolved antioxidant compounds of this invention or, in order tofacilitate the incorporation of the antioxidant or synergist into thefat or oil, they can both be dissolved in a suitable solvent which isinert insofar as concerns both the antioxidant and the synergistcomponents in the finally prepared and stabilized fats or oils.

Examples of synergists which can be employed include citric acid,phosphoric acid, ascorbic acid, as well as various other acids andsynergistic compounds described in the prior art.

In amplification of the fats and oils mentioned above which can bestabilized bythe antioxidants of our invention, various representativefats and oils include linseed oil, menhaden oil, cod liver oil, castoroil, olive oil, rape seed oil, coconut oil, palm oil, corn oil, sesameoil, peanut oil, babassu oil, butter fat, lard, beef tallow, etc., aswell as hydrogenated oils and fats prepared from any of the foregoing.Furthermore, various other oils and fats may be similarly treated withinthe scope of the present invention.

Inasmuch as it is well known in the art to employ antioxidants in thestabilization of fats and oils, it is not believed necessary to givenumerous specific examples of how the antioxidants of this invention areblended with fats and oils nor the specific proportions which can beemployed. The methods of blending anitoxidants and synergists withparticular fats and oils can be readily determined by those skilled inthe art. The range of antioxidant-proportions whichcan be employed isfrom about 0.001 percent up to as much as 1.0 percent or more by Weightof the antioxidants of this invention depending upon the effectsdesired. Generally, a range of proportions of from about 0.001 percentto about 0.1 percent is advantageous with the upper limit being usuallyfully satisfactory if .it does not exceed 0.05 percent. When solventsareemployed in preparing antioxidant solutions, suchsolvents can bepresent in an amount just sufficient to dissolve-theantioxidant up toany larger amount which maybe desired, especially if larger amounts arenecessary to fully dissolve other supplementary antioxidants and/orsynergists which may be incorporated into the antioxidant solution.

The following tabulation of data is presented in order to show theproperties .of t comp un w ich is'b lieved to be--2;2- d imethyl-5hydroxy-6-(1-propenyl)coumaran, as compared to two somewhat relatedcompounds wherein the 6-.position is occupie by 'S6QO d 'y ty radical inone instance and a tertiary butyl radical in the second instance. Theprior art indicates that these comparative compounds are among theadvantageouslyeifcctive antioxidants described prior to the instantinvention. The compound called butylated hydroxyanisole (BHA) in thistable is a mixture of the 2- and 3-isomers of monotertiarybutyl-4-hydroxyanisole with the 2-isomer predominating. BHA is awell-known commercially available antioxidant used for the stabilizationof fats and oils.

It can be seen from the preceding table that all of the antioxidantcompounds set forth therein which were known in the prior art hadreasonably good antioxidant properties for the stabilization of lard.The antioxidant of this invention, i. e.2,2-dimethyl-5-hydroxy-x-(l-propenyl)coumaran (probably the 6-isomer setforth in the above table) is markedly superior to the previously-knownantioxidants with which the comparison has been made. In fact theantioxidant of this invention is approximately twice as efiective asthese previously-known compounds.

The data presented above is based on tests conducted with three samplesof commercially available lard identified as samples Nos. 15, 16 and 17.The AOM figures are in hours; the procedure employed under the AOM(active oxygen method) is well known in the antioxidant art and need notbe explained in this specification.

In addition to the employment of2,2-dimethyl-5-hydroxy-x-(1-propenyl)coumaran in the stabilization offats and oils this antioxidant can also be employed in the stabilizationof other organic compounds such as synthetic resins, cracked gasoline,pyrethrums, etc.

The employment of 2,2-dimethyl-5-hydroxy-x-(l-propenyl) coumaran forstabilizing edible fats and oils is especially advantageous since it isrelatively insoluble in water but is soluble in various hydrocarbonsolvents and in fats and oils. This results in the antioxidant havingexcellent carry-over properties. In other words, the blending, cooking,packing or other processing operations performed in the preparation offood products has relatively little effect on the antioxidant covered bythis application. Due to the resultant carry-over effect, the productobtained has improved shelf life.

We claim: 7 V

l. A new composition of matter having the following formula (CHa):

wherein R represents a substituent selected from the group consisting ofa hydrogen atom and a i-propenyl radical.

2. 2,2-dimethyl-5-hydroxy-6-( l-propenyl) coumaran.

3. A process for preparing the composition of matter which is defined inclaim 1 which comprises heating a starting material having the followingformula:

(CH3): wherein R represents a member selected from the group consistingof a hydrogen atom and an allyl radical, in the presence of an alkalimetal hydroxide solution in an inert polar medium under an inertatmosphere at a temperature of from about to about 190 C. whereg by aproduct is produced wherein the allyl radicals present in the startingmaterial have been isomerized to form l-propenyl radicals.

4. A process for preparing 2,2-dimethyl-5-hydroxy-6-(1-propenyl)-coumaran which comprises heating 2,2-dimethyl-S-hydroxy-6-allylcoumaran in the presence of an alkali metalsolution in an inert polar medium under an inert atmosphere at atemperature of about 110 to about 190 C.

5. A process as defined in claim 4 wherein the inert atmosphere isnitrogen and the elevated temperature is about C.

6. A process as defined in claim 5 wherein the inert polar medium iswater.

7. Stabilized materials selected from the group consisting of fats andoils containing from about 0.001% to about 1.0% by weight of thecomposition of matter as defined in claim 1.

8. Stablilized materials selected from the group consisting of fats andoils containing from about 0.001% to about 0.1% by weight of2,2-dimethy1-5-hydroxy-6-(1- propenyl)coumaran. v

9. A process for stabilizing a material selected from the groupconsisting of fats and oils which comprise adding from about 0.001% toabout 1.0% by weight of the composition of matter which is defined inclaim 1.

10. A process for stabilizing a material selected from the groupconsisting of fats and oils which comprises adding from about 0.001% toabout 0.1% by weight of 2,2-dimethyl-5-hydroxy-6-( l-propenyl) coumaran.

No references cited. I

1. A NEW COMPOSITION OF MATTER HAVING THE FOLLOWING FORMULA 